Various agents and mechanisms can alter the condition of the teats of dairy cows. The alterations in teat end condition can occur over a short, medium or long term. The primary short term (ie a single milking) effects include changes in teat color, swelling and firmness of the teat and teat end as well as the degree of openness of the teat orifice. Medium term effects (ie requiring a few days to weeks) include changes in the teat skin
condition and incidence of small hemorrhages. The most significant long term effect (occurring in 2-4 weeks) is changes in the amount and character of the hyperkeratosis at the teat orifice. These long term changes may occur at a more rapid pace when coupled with extremely cold or harsh environmental conditions.
Part of the teat end barrier to the entrance of mastitis pathogens are the keratin cells that line the teat canal. These keratin cells have a sticky or adhesive property that enable them to stop pathogens from completely penetrating the teat canal. Mature keratin cells and the bacteria that are stuck to them are removed during each milking. The keratin cells are being continuously replaced as they are “washed” out at each milking.
When excessive keratin removal occurs, the keratin production of the teat canal is stimulated. The result of this stimulation may be keratin extending as projections or fronds around the teat end. This may also be accompanied by the formation of a ring around the orifice. When this hyperkeratosis or over stimulation of keratin production becomes severe, it may be associated with an increased in both non-clinical and clinical
mastitis. For this reason several systems for evaluating and scoring teat end has been developed.
An international group of mastitis workers known as “The Teat Club International” has developed a teat scoring systems that is both reliable and simple. While they have a more complex system for research studies, they also have proposed a system for field workers. This system has four classes of teat end conditions.
1. Score N - No ring, the teat end is smooth with a small even orifice.
2. Score S – Smooth or slightly rough ring with a raised ring around the orifice. The raised area may
be smooth or slightly rough. No keratin fronds is present.
3. Score R – Rough ring with raised, roughened ring with fronds of keratin extending 1-3 mm from the
4. Score VR – Very rough ring with keratin extending more than 4 mm from the orifice. The rim of the
ring may often be cracked.
Based on this scoring system, an investigation into the possible causes of the teat end conditions is recommended if more than 20% of the teats score R or VR, or more than 10% of the teats score VR. In large milking herds with large parlors is not usually possible to convienently score all the teats. Therefore a subset of cows from the entire herd can be scored. Various numbers of cows within a herd should be observed to
estimate with confidence the level of teat end conditions. Following sample sizes and findings will give an estimate at the 95% confidence level.
About 10% of the teats in a herd may be affected based on these observations:
100 teats observed, more than 5 affected
200 teats observed, more than 13 affected
300 teats observed, more than 21 affected
400 teats observed, more than 29 affected
About 20% of the teats in a herd may be affected based on these observations:
100 teats observed, more than 13 affected
200 teats observed, more than 30 affected
300 teats observed, more than 47 affected
400 teats observed, more than 65 affected
It is suggested that the observations of the teat ends be made as the milking units are removed prior to application of teat dip. A regular pattern of observation should be used and a headlamp and tape recorder have been found to useful. It is important to look both at the sides and ends of all the teats. Random sampling is suggested, however, it may be appropriate to look at a part of the herd (string or lactation group) where the problem is reported to be occurring. The authors suggest that at least 80 cows or 20% of the herd should be viewed.
Ohnstad IC, Mein GA, Neijenjuis F, Hillerton JE, Baines JR and Farnsworth R. Assessing the scale of teat end problems and their likely causes. Proceeding of the 42nd National Mastitis Council Meeting, Fort Worth, TX. January 25, 2003. Pg 128-135.
Author: John H. Kirk, DVM, MPVM - Extension Veterinarian
School of Veterinary Medicine - University of California Davis